The idea would be a squad of Tempestus Scions, one among a platoon or two under command of an Ordo Xenos Inquisitor investigating a genestealer cult on an Imperial Hive world. Enemies would include the obvious genestealers, cultists and hybrids, as well as the local gangs of the Hive world itself. Circumstances could become more complex if problems arise with the local authorities, and of course the ever present race against time to root out and excise the cult before it draws the attention of the Hive Fleets themselves.